Merge pull request #529 from google/tidy

Cleanups, comments, debug logs.

Author: jaqx0r

TODO

@@ -121,3 +121,8 @@ Should the waker move into the tailer package?
 Benchmarks on GHA are too variable.  Compute benchmarks old and new in same instance, per guidelines from "Software Microbenchmarking in the Cloud. How Bad is it Really?" Laaber et al.
 
 Move loc and useCurrentYear out of VM and into Runtime env.
+
+Move const folding into parser during AST build.
+Const-fold identity functions.
+
+Replace IndexedExpr with no ExprList with just the IdTerm.

internal/exporter/prometheus.go

@@ -46,6 +46,7 @@ func (e *Exporter) Collect(c chan<- prometheus.Metric) {
 		go m.EmitLabelSets(lsc)
 		for ls := range lsc {
 			if lastMetric != m.Name {
+				glog.V(2).Infof("setting source to %s", m.Source)
 				lastSource = m.Source
 				lastMetric = m.Name
 			}

internal/metrics/store.go

@@ -47,7 +47,6 @@ func (s *Store) Add(m *Metric) error {
 		// - copy old LabelValues into new metric;
 		// - discard old metric.
 		for i, v := range s.Metrics[m.Name] {
-			//
 			if v.Program != m.Program {
 				continue
 			}
@@ -87,6 +86,7 @@ func (s *Store) Add(m *Metric) error {
 	s.searchMu.Lock()
 	s.Metrics[m.Name] = append(s.Metrics[m.Name], m)
 	if dupeIndex >= 0 {
+		glog.V(2).Infof("removing original, keeping its clone")
 		s.Metrics[m.Name] = append(s.Metrics[m.Name][0:dupeIndex], s.Metrics[m.Name][dupeIndex+1:]...)
 	}
 	s.searchMu.Unlock()

internal/runtime/compiler/checker/checker.go

@@ -250,7 +250,7 @@ func (c *checker) checkSymbolUsage() {
 					// Don't warn about the zeroth capture group; it's not user-defined.
 					continue
 				}
-				glog.Infof("declaration of capture group reference `%s' at %s appears to be unused", sym.Name, sym.Pos)
+				glog.Infof("capture group reference `%s' at %s appears to be unused", sym.Name, sym.Pos)
 				continue
 			}
 			c.errors.Add(sym.Pos, fmt.Sprintf("Declaration of %s `%s' here is never used.", sym.Kind, sym.Name))
@@ -638,6 +638,14 @@ func (c *checker) VisitAfter(node ast.Node) ast.Node {
 			n.SetType(types.Error)
 			return n
 		}
+
+		// Having typechecked the expression against the expected types, we
+		// have detected mismatched keylengths, and can now fold to just IdTerm
+		// if there's no ExprList.
+		if len(exprList.Children) == 0 {
+			return n.Lhs
+		}
+
 		n.SetType(rType)
 		return n
 

internal/runtime/compiler/parser/parser.go

@@ -441,6 +441,7 @@ primary_expr
 indexed_expr
   : id_expr
   {
+    // Build an empty IndexedExpr so that the recursive rule below doesn't need to handle the alternative.
     $$ = &ast.IndexedExpr{Lhs: $1, Index: &ast.ExprList{}}
   }
   | indexed_expr LSQUARE arg_expr_list RSQUARE